Inductive apparatus



March 22, 1960 A. HUFNAGEL mvucnvz APPARATUS 2 Sheets-Sheet 1 Filed Jan.20, 1958 I I I I II IIIIIIIIIII I Hl H.

I0 llllll March 22, 1960 A. HUFNAGEL INDUCTIVE APPARATUS 2 Sheets-Sheet2 Filed Jan. 20, 1958 INVENTOR. flzzcflw Han/220 05.

HIS ATTORNEY tors utilize opposing pairs of United States Patent 0,

2,930,012 INDUCTIVE APPARATUS Andrew Hufnagel, Penn Township, Pa.,assignor to Westinghouse Wilmerding, Pa., a corporation AlleghenyCounty, Air BrakeCompany,

of Pennsylvania My invention relates to inductive apparatus, and particularlyto an; improved construction for reactors, transformers, andthelike having cores madeof highly efficient grain oriented magneticsteels.

Iron core reactors are widely used in decoding units for'coded traincontrol and coded wayside signal applications. Generally, in such adecoding unit, a reactor, is connected, in series; with a fixedcondenser, andthe resultanttuned circuit is adjustedto the desiredfrequency by varying an air gap in the magnetic structure of thereactor.

Two forms of adjustabletcore reactors which have heretofore been widelyused :are :shown and described'in Letters :Patent'of the UnitedStatesNo. 1,869,364, granted August 2, 1932 to Leslie R. Allison, forReactors, and .No. 2,446,624, granted August 10, 1948 to Leslie R.Allison, for Reactance Devices, both assigned to thesame assignee as thepresent application. Both of these reacflat .E-shaped laminationsmounted with their legs confronting each otherso asto formair gaps.between them. Thelaminations are made of the usual type of transformersteel.

Since these reactors were developed, newer magnetic materialshave becomeavailable havinglower magnetic losses than heretofore obtainable, whenthe flux is in a particular direction therein. border to cause the fluxto traverse these materials in the proper direction, the materials arerolled into strips which are wound into a multi-layer, closed magneticloop usually held together byabanding strap. A core formed in thismanner'does not readily lend itself to the having an adjustable air gapfor circuit tuning purposes, and one object of my invention is toprovide an economical reactor design which will enable these'ncwermagnetic materials to be used in tunedcircuits.

Another object of my invention is to provide a reactor having a windinglinking a wound layer type of core, includingone or more air gaps, andin which the entire structure is'secured together by straps heldin placeby a single clamping bolt.

Another object of my invention is to provide inductive apparatus of thetype described that is compact and rugged, and which employs simple andeasily manufactured parts.

. A; further object of my invention is to provide a' novel 'formofreactor, including means for varying the inductance of the reactor atthe. time of assembly, and which may be readily returned in thejfiel'dto .meet a particular circuit requirement.

Other objects, purposes, and characteristic features of my inventionwill be in part obvious from the accompanying drawings and in partpointed out as the description proceeds.

In practicing my invention in accordance with one embodiment thereof, iprovide a pair of magnetic cores each formedby winding asingle,flatsteel strip inamulti-layers to :form a closed magnetic loop. Eachcore isathen .separated to form upper and lower U shaped membershavmanufacture ofa reactor 2,930,012 Patented Mar. 22, 1960 ingconfronting legs with confronting faces normal to the axes of the legs.The lower U shaped members are placed in juxtaposition on a base plate,the axes of the confronting legs of the members being normal to theplate. Fixed and adjustable shims are placed on the faces of, the insideand outside confronting legs, respectively. A preformed coil is disposedabout the inside legs of the lower members, and the upper U shapedmembers are then positioned so that their legs confront the legs of thelower U shaped members with the shims interposed therebetween. Thecores, coil plate and shimsare rigidly secured in an assembled positionby enclosing straps, securing blocks and a spacer bushing, all of whichare apertured to receive a common bolt which isthreadably engaged by oneof the blocks.

In tuning a reactor so constructed, the bolt is loosened to permitlongitudinal movement of the adjustable shims until the desired level ofinductance of the reactor is obtained. The bolt is then tightened tofirmly securethe parts in their adjusted positions.

It is to be understood that my invention is not to be restricted to areactor, but is applicable, in its broader aspects, to transformers andinductive apparatus requiring a core of the class described for itsoperation.

I shall describe one embodiment of my invention, and shall then pointout the novel features thereof in claims.

In describing my invention, reference will be made to the accompanyingdrawings, in which corresponding parts are identified by correspondingreference characters and in which:

Fig. 1 is a front elevational view of a'reactor assembly embodying myinvention.

Fig. 2 is a top plan view of the in Fig.1.

Fig. 3 is an enlarged perspective view of the retaining assembly of thereactor shown in Figs. 1 and 2.

Fig. 4 is an enlarged perspective view of a bimetallic shim employed inthe reactor.

Referring to Figs. 1 and 2, a reactor assembly 1 is shown comprising acoil 2 of conventional construction mounted inv winding spaces 3 and 4formed by two core loops 5 and 6 placed side by side.

The core loops 5 and 6 are each Wound of continuous strips of grainoriented magnetic steel providing high electrical efficiency so long asthe flux traversesthe material in a lengthwise direction, and are thenseparatedinto upper U shaped members 7 and lower U shaped members 8having the legs 7a and 7b and 8a and 8b, respectively, with confrontingfaces normal to the axes of the legs 7a and 7b and 8a and 8b. Theconfronting faces of legs 7a, 7b, 8a and 8b are ground smooth to keepmagnetic reluctance to a minimum.

A base plate 9 supports the lower U shaped members 8. The base plate 9has a central aperture 9a and is recessed at 9b on opposing sidesparallel to the lengthwise direction of the strip stock forming coreloops 5 and 6. Mounting holes 96 are formed in each corner of base plate9 to facilitate securing the reactor assembly 1 to any desired supportstructure. The lower U shaped members 8 are placed in juxtaposition onbase plate 9 in such a manner that the inside legs 8a are adjacent, andthe axes of legs 8a and 8b are normal to plate 9 (Fig. 1).

Fixed shims 10 and adjustable shims 11 are placed on the faces of legs8a and 8b. The fixed shims 10 may be of either magnetic or nonmagneticmaterial, depending upon the general level of inductance required in thereactor. The adjustable shims 11 are bimetallic and comprise a portionof suitable magnetic material, such as silicon steel, and a portion ofnonmagnetic material, such as Phosphor bronze,joined-inend-toendrelation by any convenient means, such as butt welding(see Fig.

reactor assembly shown 4); The shims 10 and 11 have the same thickness,so that when the reactor is assembled and members 7 and 8 are drawntightly together, full surface contact will take place between the shimsand confronting faces of legs 7b 8b and 7a-8a, respectively. a Apertures3 and 4 formed by core loops 5 and 6 receive coil 2. After coil 2 isdisposed about adjacent inside legs 8a of lowermembers 8, upper U shapedmembers 7 are positioned with respect to members 8, so that confrontingfaces of legs 7a and 8a and 7b and 8b confront fixed shims 10 andadjustable shims 11, respectively (Fig. l). Referringnow to Figs. 2 and3, assembled core loops 5 'and6, coil 2, and plate 9 are securedtogether by a retaining assembly 12. The assembly 12 comprises straps12a, encircling the periphery of each'of the core loops 5 and 6, blocks12b and 12g, plates 120, a spacer bushing 12d and a bolt 12e. Each endof straps 12a is secured between a block 12b or 12g, 7 by; anyconvenient means, for example, by rivets (Fig. 3). The' straps 12a,blocks 12b and 12g,-plates 12c, and spacer bushing 12d are provided withaligned apertures to receive the bolt 12a. The aperture 12h in the block12g is threaded to engage threads provided on bolt 12e, whereby all ofthe parts may be secured together by means of the bolt 12c. On bothblock 12g and bolt 12c a large number of threads with a small clearancetolerance are used so that a lock nut is not required to retain the boltin its tightened position. Spacer bushing 12disprovided to maintain arigidly braced assembly which tends to prevent core loops 5 and 6 frombowing at a top center position 13 defined by adjacent legs 7a of upperU shaped members 7 (see Figs. 1 and 3).

As best shown in Figs. 1 and 3, plates 12:: bear on core loops 5 and 6at 7c, and blocks 12b and 12g bear on straps 12a at 14. The thickness ofstraps 12a added tothe height of block 12b or 12g equals the height ofplates 12c. This arrangement permits block 12b or 12g and straps 12a toform a nearly right angle with core loops Sand 6, when firmly secured,so as to rigidly retain reactor assembly 1. The blocks 12b and 12g, inbearing on straps 12a, force straps 12a to bear against core loops 5 and6, thereby maintaining the shape and position of the'core loops.

As shown in Figs. 1 and 2, one of straps 12a, having its ends securedbetween block 1% or 12g and plate 120, encircles the periphery of coreloop 5 and secures core loop 5 to base 9 by engaging recess 9b andpassing through aperture 9a. In a similar manner core loop 6 is securedto base 9. Spacer bushing 12a is then placed into position as shown inFigs. 1, 2 and 3, and bolt 12:: is inserted within the aligned aperturesin straps 12a, block 12b, plates 12c, and spacer bushing 12d, andretaining assembly 12 is tightly secured through the threaded engagementof bolt 12c and block 12g.

With reactor assembly 1 and retaining assembly 12 constructed andarranged in the manner described, bolt 12e is initially not fullytightened, thereby permitting a 'longitudinal movement of bimetallicshims 11 (see Fig. 2). The positions of bimetallic shims 11, betweenlegs 7b and 8b, are varied simultaneously in a longitudinal direction toobtain the desired tuning by varying the reluctance of core loops 5 and6. The bimetallic shims 11 are varied simultaneously to preventunbalanced magnetic fiuxes in the two core circuits. With thenonmagnetic portions of bimetallic shims 11 in core loops 5 and 6, thereluctance will be at a high value, equivalent to the reluctance of anair gap. From test data taken on an experimental model, it was foundthat as the magnetic portions of bimetallic shims 11 are moved into coreloops 5 and 6 at 7b-8b, the inductance of reactor assembly -1 increasesin a fairly linear fashion. The linearrelation continues until. there isso much of the and a plate 12c 7 magnetic portions of bimetallic shims11 within core loops 5 and 6 that the magnetic portions of the shims areno longer saturated. A further insertion of the shims will increase theinductance to a progressively lesser extent, because the cross-sectionalareas of the inserted ,magnetic portions are now approaching thecross-sectional areas of the core loops. For this reason, the mag neticportion of bimetallic shims 11 need not be as long as the nonmagneticportion. The positions of bimetallic shims 11 are varied within coreloops 5 and 6 until the circuit is found to be in tune and reactorassembly 1 is then locked securely in place through threaded engagementbetween bolt 12c and block 12g.

Should it be necessary to retune reactor assembly 1 in the field, it isa relatively easy matter to loosen bolt 12e, reposition bimetallic shims11 to a new level of inductance by the method previously described, andthen retighten bolt 12c so reactor assembly 1 is rigidly secured.

Although I have herein shown and described only one form of .a -reactorembodying my invention, it is to be understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A reactor, comprising, in combination, a base plate having acentrally located opening, a pair of multi-layer wound magnetic coreseach having first and second generally U shaped members in a confrontingrelation with confronting legs and confronting faces, each of said firstU shaped members being disposed on said base plate and having adjacentinside legs and spaced apart outside legs normal to said base, a coildisposed about said inside legs and confined by said first and second Ushaped members in said confronting relation, adjustable shims disposedbetween confronting faces of said outside legs and fixed shims disposedbetween confronting faces of said inside legs, first and second strapseach having first and second ends, first and second blocks and plates,said first endsof said straps being secured between said first blocksand plates, each of said straps passing along the outside edge of one ofsaid cores, then under said base plate, through said opening and alongthe inside edge of the said one of said cores, said second ends beingsecured between said second blocks and plates to secure said cores tosaid base plate, a spacer bushing disposed between adjacent second endsof said straps to position said cores on said base plate, a boltreceived within aligned apertures in said straps, blocks, plates andspacer bushing, and one of said first blocks threadably engaging saidbolt, whereby said reactor may be rigidly held together or loosened topermit adjustment of said adjustable shims to vary the inductance insaid reactor.

2. In a reactor, grain oriented magnetic strip material having maximumflux carrying properties in the direction of the grain orientation ofsaid material and wound in multi-layers to form a pair of cores, each ofsaid cores comprising first and second U shaped members in a confrontingrelation having confronting legs with confronting faces, a mountingplate having a centrally located opening, said plate engaging a closedend of said first U shaped members which form a pair of adjacent insidelegs and a pair of spaced apart outside legs normal to said plate, acoil disposed about said inside legs and confined by said first andsecond U shaped members in said confronting relation, fixed shimsdisposed between 'confronting faces of said inside legs, and adjustableshims disposed between confronting faces of said outside-legs, aretaining strap running along the outside edge ofeach of said cores,passing under said plate, through said opening, and running along theinside edge of each of said cores, and having ends terminating adjacentthe closed ends of said second U shaped members, and adjustable meansfor securing said ends, whereby said'reactor can be rigidly heldtogether or loosened to permit adjustment of said adjustable shims tovary the inductance of said reactor.

3. In an inductor, a pair of substantially rectangular cores eachcomprising two generally U shaped pieces having abutting joints betweenthe respective ends of the two pieces, said cores being arrangedrelative to each other to form substantially parallel outer legs and apair of adjoining inner legs, at least one shim disposed betweenrespective abutting joints of the inner and the outer legs of saidcores, a coil disposed about said inner legs of said cores, a supportplate for said cores and a hole in said plate, means for securing eachof said cores to said plate running along the outer edge of each of saidcores and under said plate, through said hole in said plate, and alongthe inner edge of each of said cores, the ends of each of said securingmeans terminating adjacent each other and having secured thereonenlarged portions for reinforcing said ends, means for spacing the innerones of said ends of said securing means a predetermined distance apart,said spacing means, said ends of said securing means, and said enlargedportions each being provided with an aperture, and a single bolt formoving the ends of each of said securing means toward each other passingthrough said apertures and becoming threadably engaged to the last oneof said enlarged portions through which said bolt passes.

4. Inductive apparatus of the class described comprising a pair ofsubstantially rectangular cores each comprising two generally U shapedcore members having abutting joints, said pairs being arranged relativeto each other forming two spaced apart outside legs and two inside legsin juxtaposition, at least one shim disposed between respective abuttingjoints of the inside legs and the outside legs of said pairs of coremembers, a coil mounted on said inside legs, a mounting plate engagingadjacent bight portions of two of said core members and a hole in saidplate, straps for binding each of said cores to said plate, each of saidstraps being adapted to extend along the outer edge of the outside legsof each of said cores and under said plate, through the hole in saidplate, and along the inner edge of the inside legs of each of saidcores, the ends of each of said straps terminating adjacent each otherand having secured thereon means for reinforcing said ends, means forspacing the innermost ends of each of said straps a predetermineddistance apart, said spacing means, the ends of said straps, and saidreinforcing means each being provided with a hole, and fastening meanspassing through said holes and being adapted to adjustably engage thelast one of said reinforcing means through which said fastening meanspasses, whereby by loosening said fastening means, adjusting thepositions of said shims at said outside legs, and retightening saidfastening means the reluctance of said core can be varied to provide anydesired value of inductance in said core.

5. Inductive apparatus, comprising, in combination, four generally Ushaped magnetic core members, each of said members having its legsconfronting the legs of one other of said core members to form first andsecond pairs of core members, said first and second pairs of coremembers being disposed in parallel planes with one side of each of saidpairs forming adjacent inside legs, a coil mounted on said inside legs,a mounting plate for said pairs of core members disposed normal to theaxes of the legs of said core members, a pair of straps each beingadapted to substantially encircle one pair of said core members andbeing further adapted to engage said plate to thereby rigidly hold thatpair of core members against said plate when the ends of the strapassociated therewith are drawn together, first means mounted to the endsof said straps for reinforcing said ends, means for spacing the innerends of said straps a predetermined distance apart, said spacing means,said first means, and said strap ends each having a hole, and means fordrawing the ends of each of said straps toward each other being adaptedto pass through said holes and being further adapted to threadablyengage the last one of said first means through which said last namedmeans passes.

6. In a reactor, a substantially rectangular magnetic core comprising apair of generally U shaped core members having confronting legs formingabutting joints, a mounting plate for said core members disposed injuxtaposition with the bight portion of one of said core members, atleast one shim disposed between the abutting joints of said legs, a coilmounted on confronting legs of said core members in such manner that theshim between the abutting joints of the other of the confronting legs isaccessible for adjustment, a strap being adapted to substantiallyencircle said core and being further adapted to engage said plate sothat the force holding said shims in place is progressively increased asthe strap ends are drawn toward each other, a hole in each of said strapends, and means for moving the strap ends toward each other, therebytightening said strap about said core, said last named means being inthe form of a single bolt adapted to pass through said holes and beingfurther adapted to threadably engage said strap ends so that when saidbolt is loosened the shim may be positioned to change the reluctance ofsaid core and thereby change the inductance of said coil.

References Cited in the tile of this patent UNITED STATES PATENTS2,165,055 Kaflca July 4, 1939 2,459,374 Goodrich Ian. 18, 1949 2,655,717Dunn Oct. 20, 1953 2,835,876 Hammond May 20, 1958

